Cough reflex responses during pulmonary C-fibre receptor activation in anesthetized rabbits.
We investigated the changes induced by pulmonary C-fibre receptor activation in the cough reflex evoked by mechanical stimulation of the tracheobronchial tree in pentobarbitone anesthetized, spontaneously breathing rabbits. Phrenic nerve and abdominal muscle activities were monitored along with tracheal and arterial blood pressures. The activation of pulmonary C-fibre receptors by means of right atrial injection of phenylbiguanide (PBG) caused the pulmonary chemoreflex characterized by tachypnea, bradycardia and hypotension. During the pulmonary chemoreflex, the time components (total cycle duration, inspiratory and expiratory times) of the cough motor pattern significantly decreased, whereas no consistent changes in peak phrenic and abdominal activity, peak tracheal pressure and number of coughs evoked by each stimulation trial were observed. At variance with previous findings in cats and dogs, the results show that tracheobronchial cough is not significantly reduced in the rabbit during PBG-induced chemoreflex. This study is the first to provide evidence supporting the hypothesis that the time components of the cough motor pattern are, to some extent, dependent upon the timing characteristics of the ongoing respiratory activity and suggests a novel mechanism leading to cough depression.
Mutolo
Donatella
D
Dipartimento di Scienze Fisiologiche, Unità Funzionale di Medicina Respiratoria, Università degli Studi di Firenze, Viale G.B. Morgagni 63, 50134 Firenze, Italy.
Bongianni
Fulvia
F
Cinelli
Elenia
E
Fontana
Giovanni A
GA
Pantaleo
Tito
T
D000009:Abdominal Muscles / Q000502:physiology; D000818:Animals; D001645:Biguanides / Q000494:pharmacology; D001794:Blood Pressure; D002404:Catheterization; D003371:Cough / Q000503:physiopathology*; D004576:Electromyography; D006339:Heart Rate; D008297:Male; D009043:Motor Activity / Q000502:physiology; D036421:Nerve Fibers, Unmyelinated / Q000502:physiology*; D010791:Phrenic Nerve / Q000502:physiology; D011661:Pulmonary Stretch Receptors / Q000187:drug effects / Q000502:physiology*; D011817:Rabbits; D012018:Reflex / Q000187:drug effects / Q000502:physiology*; D014132:Trachea / Q000502:physiology
D001645:Biguanides; C008846:phenyl biguanide